Hi maverick and other helpful fellow geeks...

I have "a bit of a doozy" of a problem (WxC Tech Support's words) with my SPA2102 VoIP router, on an XNet Fusion ADSL plan.
... and I hope you can help... otherwise I will have to call WxC back to log a proper trouble ticket if I can't resolve this in the next few days.

Context:

• PPPoA to Ethernet bridge modem: D-Link DSL-300T (Normally any PC or router can pull the proper WAN IP and DNS servers via DHCP from XNet, so it is nakedly/directly connected to the DSL network).
  Details: http://www.thinkbroadband.com/hardware/reviews/2004/q4/dlink-dsl300t.html
  G.dmt ADSL link speed: 7616kbps down / 896kbps up  (Rock on Chorus!)
   
• NAT Router: SMC Barricade SMC2804WBR 802.11g -- solid, has run like a charm for me since 2004 under heavy punishment.
  Details: http://reviews.cnet.com/routers/smc-smc2804wbr-barricade-54mbps/1995-3319_7-21100137.html
   
• The SPA2102 device connects and establishes the line properly when set with Static IP on the WAN side, behind my existing NAT router... but...

Problem:

• The SPA2102 does not pick up a valid WAN IP address or DNS IPs when set to DHCP on the WAN interface when connected to the DSL-300T, with or without the SMC plugged into the LAN-side.  (ie. The Xnet BRAS doesn't play nicely with the SPA2102... Did disclosing it's MAC address doom it to a life of exclusion?! ),
  This seems very strange, as every other device I have owned, including a 'Lingo' VoIP ATA with inline bridge-mode QoS from VoIP provider Primus Communications (of the USA), has worked just fine behind this modem, and with the SMC router as the LAN-side client. 
   
• Aside from that, and frustratingly, the 'Bridge mode' in the SPA2102 does not seem to work (even when my IP address range on the LAN side is not in conflict, per other suggested fixes in threads on these Geekzone forums).  So with the SPA2102 in the place where it logically should be, in between modem and router so it can prioritise voice, the SMC now can't get the DHCP WAN IP and DNS IPs like it normally does from the DSL-300T.  (Bah! humbug! Not only does the SPA2102 not work... it also breaks everything else!)
   
• Then, in the current setup, with the SPA2102 behind my SMC (so it's in my LAN), the SPA2102 is owning my LAN: killing my internet connection's usability. (I thought it only needed 64kbps up and down?!)
   
• Additionally, because of being located behind the NAT along with our laptops/PCs, the SPA2102 is not able to apply a QoS priority to voice traffic over data traffic... I anticipate that this will hurt our VFX service's usability when we're hammering the data connection... the routine problem faced by Linksys PAP2T basic ATA users. 
   

Next steps:

• If possible, I will try spoofing a (laptop-like ) MAC address and hostname on the SPA2102's WAN side to see if that
  allows me to properly get a WAN IP and DNS IPs from the Xnet BRAS.
   
• Then tonight I'm going to try a Zyxel Prestige 660HW ADSL2+ modem/router (using it only as the ADSL modem; ie. with SPI, Media Bandwidth Management, and the built-in 802.11g AP all disabled) with the SPA2102 behind it, and a standard 802.11g Access-point (non-NAT) on the SPA2102's LAN-side.  So the SPA2102 should then be my NAT router as well as ATA with voice-priority over data. 
  Unfortunately, I think the Zyxel will insist on NAT'ing as well... but that shouldn't be a show-stopper... all the sessions should carry through correctly (the proof being my ability to use the SMC to NAT LAN traffic onto its Ethernet WAN port while also sitting behind the Zyxel which NATs sessions onto the DSL connection oblivious to the fact that they've already been NAT'd by the SMC).
  
  ... and I'll report back tomorrow. 

How to help?

• VFX users: Have you experienced similar issues with the SPA2102?  (My one is an Xnet-packaged original, new, and provisioned correctly after I used Static IP on the WAN side behind my existing NAT router.)
   
• WxC staff: Any ideas on the WAN-side DHCP issue with the SPA2102?  Are there any known incompatibilities with ADSL modems?  (I bought the SPA2102 rather than a WAG54GP2 as I was hoping to one day move to a fibre-based access solution with Xnet and maintain my VFX line seamlessly while changing the access line... and maybe I'll also carry the unit around with me to other locations to use VFX service from there... eg. hotels, my parent's house on Orcon ADSL, and my mate's place on an NZWireless 802.11b last-mile access network... ie. Places where I'll also connect my laptop by Ethernet, preferably to the LAN-side of the SPA2102.) 
   
• WxC or C1 (to assist in trying my solution of last resort): offer a trade-in on my SPA2102 for a WAG54GP2v2, pleeease?  (And cross fingers that it works!) 

Thanks in advance for your assistance!

~Heath